wort

Wort is the sugar-rich liquid that results when crushed malt or grain is steeped in hot water, then filtered or run off from the solid matter. In brewing and distilling, this intermediate product is the actual feedstock for fermentation: yeast eats the sugars in wort and produces alcohol and carbon dioxide. Without wort, there is no beer, whisky, or other grain-based spirit. The word comes from Old English and German roots meaning simply "plant" or "herb," a reminder that grain itself was once grouped with medicinal plants in trade vocabulary.

The process of creating wort is called mashing. Malt, which is grain that has been steeped, allowed to germinate, and dried in a kiln, is crushed and mixed with hot water, typically between 65 and 77 degrees Celsius depending on desired sugar profile and enzyme activity. The temperature and duration control which sugars dissolve and which enzymes remain active. After 30 minutes to several hours, the liquid is run off through the grain bed itself, which acts as a filter. This liquid is the wort. The remaining wet grain solids, called spent grain, are often sold for animal feed.

Wort must be boiled before it can be safely fermented. During the boil, which lasts 60 to 90 minutes in brewing, hops are added at intervals to provide bitterness, aroma, and preservation. The boil also sterilizes the wort, coagulates proteins that would cloud the final product, and concentrates the liquid through evaporation. In distilling, the boil may be shorter or the wort may go directly to fermentation depending on the spirit style. After cooling, the wort is transferred to a fermentation vessel where yeast is pitched.

Composition and variation

Wort composition varies based on grain bill, mash temperature, and water chemistry. A typical wort from pale malt might contain 10 to 15 percent dissolved sugars by weight, mostly maltose and glucose. Darker malts, roasted grains, and specialty malts contribute different sugar profiles, colors, and flavors. A brewer or distiller measures wort strength using specific gravity or Brix, which indicate how much sugar is present. High gravity worts, above 1.080 specific gravity, ferment slowly and can stress yeast; low gravity worts, below 1.040, ferment quickly but yield less alcohol.

Problems in wort production affect everything downstream. Stuck mash, where the grain bed compacts and liquid cannot drain, requires careful sparging (rinsing) technique and proper crush size. Infection of wort before or during fermentation, from wild yeast or bacteria, will produce off-flavors or complete spoilage; this is why sanitation of all equipment and cooling to safe temperatures before pitching yeast are non-negotiable. Oxidation of wort, especially during cooling and transfer, can lead to stale flavors in the final product. High-protein grains or poor mashing technique can yield cloudy wort that is harder to clarify, though some cloudiness will drop out during fermentation and after cooling.